可移动装配式林业索道支架受力分析

Analysis and design of movable and assembled forest cableway support

支架是集材索道系统的重要组件,用以承托钢索,保证索道有足够的净空高度。但传统的南方人工林集材作业中多数采用活立木作为索道支架,活立木受其生长位置限制,难以保证最优集材路线,不适应现代小规模木材采集需求,为解决人工林索道集材中难以寻找合适的活立木作支架问题,研究设计出一种分段组合加绷索固定的可移动装配式钢管支架。通过力学和仿真分析,对承索方式、不同分段比例及绷索固定位置进行了优化。当分段位置于杆件的0.59L处时,效果最好,抗压能力是没有分段时的1.7倍。支架采用索鞍托索,使支架受力由传统的以承受弯矩为主变成以承受压力为主,改善了支架的受力条件。同时支架中间设置绷索固定后,增加了支架的约束条件,减小了支架的柔度,支架的临界载荷比无绷索固定的支架提高3倍以上。支架设计成分段可拆,降低了单个支架部件的重量,单个部件最大不超过50kg,便于在林区转移安装;支架采用标准镀锌管制造,取材方便,成本低廉,有利于降低索道系统成本。经试验及生产验证,可移动装配式林业索道支架转移、架设方便,使用安全可靠,特别适合山地林区择伐与小规模皆伐集材需要,对在人工林集材作业中推广小型索道集材,减小集材作业对生态环境的影响具有重要的意义。

The support structure is a major component of a cableway system,as it supports the cable and ensures that the ropeway has sufficient headroom.However,most traditional cableways in southern plantations use a living stand as the support structure.The living stand is limited by its growth position.Therefore,guaranteeing an optimal skidding route is difficult.In addition,it does not meet the requirements of modern small-scale wood collection.To solve the problem of finding a suitable living stand for the support of an artificial forest cableway,a movable sectional support fixed by cables was designed in this study.The support mode,segmentation ratio,and fixed position of the cable were optimized based on mechanical and simulation analyses.An optimal pressure resistance was obtained when the segment was located at 0.59 L of the rod,which was 1.7 times greater than that without the segmentation.A cable saddle was used,allowing the force of the support to be changed from the bending moment to the pressure,and the stress condition of the support was improved.Simultaneously,the tight cable fixture increased the constraint condition and reduced the flexibility of the support structure.The strength of the cable-fixed support was tripled as compared to the support without cable fixing.The segmented design reduced the weight of individual components,and the maximum single weight was less than 50 kg,thus enabling the support to be easily transferred and installed.The support was made of cost-effective standard galvanized pipe.Following trial and production verification,the movable and assembled forest cableway support was determined to be safe and reliable as well as convenient to transfer and erect.This type of support structure is particularly suitable for selective cutting in hilly and mountainous forest areas as well as for small-scale clear cutting.Promoting small cableway skidding in artificial forest logging work is critical to reducing the impact of logging operations on ecological environments.